Microwave heating method in multimode cavity based on wedge-shaped dielectric plates

The present invention claims priority under 35 U.S.C. 119 (a-d) to CN 202311362368.8, filed Oct. 19, 2023.

The present invention relates to a technical field of microwave heating, and more particularly to a microwave heating method in a multimode cavity based on wedge-shaped dielectric plates.

Microwave heating, as a fast and efficient heating method, is widely used in a variety of fields such as food processing, material treatment, and medical fields.

Conventional microwave heating equipment mainly consists of a microwave source, a waveguide, a cavity and a load. However, the conventional microwave heating technology still has some problems in heating efficiency, uniformity and adaptability, wherein one of the core problems is the inconsistent heating efficiency for different loads. Microwave heating is a heating process that utilizes the interaction between electromagnetic waves and matter, which triggers molecular vibration and friction for heating. Compared with the traditional heat conduction method, microwave heating has the following advantages: (1) high heating efficiency: microwave energy can be directly converted into thermal energy inside the matter, leading to fast heating speed and high efficiency of energy utilization; (2) uniform heating: microwave energy can be reflected and scattered many times inside the matter, leading to a more uniform heating effect;

(3) flexible temperature control: microwave heating is capable of rapid heating up and rapid cooling down, leading to high temperature control accuracy; and (4) being eco-friendly: microwave heating involves no fossil fuels, and generates no soot and exhaust, leading to less pollution to the environment. Despite the above advantages, microwave heating is still facing some problems in practice. One of the core problems is the inconsistent heating efficiency for different loads. When heating different loads, the conventional microwave heating method suffers from uneven distribution of microwave energy due to shape, size, material properties and location of the load. As a result, part of the areas may be overheated, while other areas may be heated insufficiently.

Conventional microwave heating methods typically employ waveguides or cavities to transmit and radiate microwave energy directly to the load. However, such methods may be restricted when heating loads of different shapes and materials. Waveguide and cavity are usually designed for loads of a particular shape or size, which are less effective when heating loads of other shapes or sizes.

In view of the above, an object of the present invention is to provide a microwave heating method in a multimode cavity based on wedge-shaped dielectric plates, thereby providing high heating efficiency.

The present invention provides a microwave heating method in a multimode cavity based on wedge-shaped dielectric plates rather than a hypersurface having gradient refractive indexes, comprising steps of:

Preferably, the microwave heating method comprises specific steps of: simulating properties of a hypersurface having gradient refractive indexes by optimizing parameters of the wedge-shaped dielectric plates, so as to enable unidirectional propagation of microwaves; wherein the parameters comprise slopes and dielectricities of the wedge-shaped dielectric plates;

Preferably, the microwave heating method further comprises optimizing an asymmetric waveguide, which comprises specific steps of:

Preferably, irrelevant variables are kept constant, and parameters are optimized with a simulation model to obtain values of the dielectric constants of the wedge-shaped dielectric plates and the bottom material corresponding to a highest heating efficiency; wherein the irrelevant variables comprise load dielectric constants, load shapes and sizes, load heights, tray thicknesses, and tray dielectric constants.

Preferably, the microwave heating method further comprises using an asymmetric waveguide to perform microwave heating experiments with different tray dielectric constants and radii, so as to heat the arbitrary loads in the multimode cavity, which comprises specific steps of:

Preferably, the microwave heating method further comprises using an asymmetric waveguide to perform microwave heating experiments with different load dielectric constants and loss angles, so as to heat the arbitrary loads in the multimode cavity, which comprises specific steps of:

Preferably, the microwave heating method further comprises using an asymmetric waveguide to perform microwave heating experiments on different loads, so as to heat the arbitrary loads in the multimode cavity, which comprises specific steps of:

Preferably, the microwave heating method further comprises using an asymmetric waveguide to perform microwave heating experiments on different load shapes, so as to heat the arbitrary loads in the multimode cavity, which comprises specific steps of:

With the foregoing technical solution, the present invention has the following advantages: energy utilization is improved, so that the heating efficiency of loads with different shapes, volumes, and relative dielectric constants can exceed 90%, thereby heating arbitrary loads efficiently.

The present invention will be further described in conjunction with the accompanying drawings and embodiments. It is clear that the described embodiments are only a part of all embodiments of the present invention. All other embodiments obtained by those skilled in the art should fall within the protection scope of the present invention.

Referring to, the present invention provides an embodiment of a microwave heating method in a multimode cavity based on wedge-shaped dielectric plates. According to the embodiment, in order to demonstrate the application of asymmetrically propagating waveguide, microwave heating experiments were firstly performed with different tray thicknesses, tray dielectric constants, load positions, load dielectric constants, load shapes and load sizes. Secondly, microwave heating efficiencies of a conventional microwave system and the method of the present invention are compared by simulation. All the results show that the present invention can efficiently heating the loads within a wide range of dielectric constants.

S1: determining effects of dielectric constants of wedge-shaped dielectric plates and a bottom material on heating efficiency; wherein the bottom material refers to a matter of a same material as the wedge-shaped dielectric plates, which covers a bottom of the multimode cavity;

S: determining effects of heights of the wedge-shaped dielectric plates and the bottom material on the heating efficiency;

S: determining effects of the load positions on the heating efficiency;

S: determining effects of the tray dielectric constants and radii on the heating efficiency;

S: determining effects of the load dielectric constants and loss angles on the heating efficiency;

S: determining effects of the load sizes on the heating efficiency;

S: determining effects of the load shapes on the heating efficiency;

The present invention aims to improve the heating efficiency of microwave multimode cavity for heating different loads using the wedge-shaped dielectric plates and the dielectric material covering the bottom of the multimode cavity. By introducing the wedge-shaped dielectric plates between the load and the microwave cavity, microwave energy can be effective transferred, thus improving the heating efficiency for loads of various shapes and sizes. This novel microwave heating method has a wider application prospect and can play an important role in a number of fields such as food processing, material treatment and medical field. In summary, the innovation of the present invention lies in the use of the wedge-shaped dielectric plates to improve the heating efficiency of the microwave cavity for heating different loads, which solves the problem of low heating efficiency of the conventional microwave heating method when heating different loads. With this novel microwave heating method, the heating efficiency and load adaptability can be improved, which has important application value and economic benefits.

Finally, it should be noted that the above embodiments are only described to illustrate the technical solutions of the present invention and are not intended to be limiting. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the specific embodiments of the present invention may still be modified or replaced by equivalent ones, and that any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the protection scope of the following claims.